[_Controverted Questions_, 1892]

Le plus grand service qu'on puisse rendre à la science est d'y faire
place nette avant d'y rien construire.--CUVIER.


Most of the Essays comprised in the present volume have been written
during the last six or seven years, without premeditated purpose or
intentional connection, in reply to attacks upon doctrines which I
hold to be well founded; or in refutation of allegations respecting
matters lying within the province of natural knowledge, which I
believe to be erroneous; and they bear the mark of their origin in the
controversial tone which pervades them.

Of polemical writing, as of other kinds of warfare, I think it may be
said, that it is often useful, sometimes necessary, and always more or
less of an evil. It is useful, when it attracts attention to topics
which might otherwise be neglected; and when, as does sometimes
happen, those who come to see a contest remain to think. It is
necessary, when the interests of truth and of justice are at stake.
It is an evil, in so far as controversy always tends to degenerate
into quarrelling, to swerve from the great issue of what is right and
what is wrong to the very small question of who is right and who is
wrong. I venture to hope that the useful and the necessary were more
conspicuous than the evil attributes of literary militancy, when these
papers were first published; but I have had some hesitation about
reprinting them. If I may judge by my own taste, few literary dishes
are less appetising than cold controversy; moreover, there is an air
of unfairness about the presentation of only one side of a discussion,
and a flavour of unkindness in the reproduction of "winged words,"